By: Robert G. Bell
Pain is a symptom of a known or unknown cause. As described in a previous post, pain can be acute or chronic, nociceptive or neuropathic, and pain tolerability is unique to the individual. If drug free remedies are not alleviating the pain, pharmacotherapies such as analgesics are usually recommended to control the symptoms of pain. The term “analgesia” derives from Greek meaning “without pain,” something most of us would welcome through life. Analgesic drugs act on the peripheral and central nervous system, blocking the transmission of pain signals centrally and upregulating the descending pain modulatory pathways. Analgesic drug products include acetaminophen, steroids (e.g., prednisolone) and non-steroidal anti-inflammatories (e.g. naproxen). The type of pain will determine the choice of analgesic. Traditional analgesics are effective in treating osteoarthritis and muscle-skeletal pain but are less effective when treating neuropathic pain. Neuropathic pain is mostly better alleviated with the use of tricyclic antidepressants and anticonvulsants.
The World Health Organization (WHO) has published a three step treatment plan. The first step is non-opioid treatment, followed by a weak opioid, and then, if needed, a stronger opioid. For today’s discussion, let’s focus on non-opioid drug therapies associated with the WHO’s step 1: take two aspirins and call me in the morning. The non-opioid drugs include acetylsalicylic acid (aspirin), acetaminophen, ibuprofen, ketoprofen, indomethacin, naproxen, diclofenac, plus many more. NSAIDs reduce pain by altering the sensation of pain by blocking certain enzymes (e.g., cyclooxygenase enzyme system) that participate in the pain response. They also work to reduce swelling that is often associated with certain types of pain. Some NSAIDs, however, are only effective at reducing swelling when taken at higher doses, which tend to trigger associated drug adverse events.
Aspirin has been used for centuries as an analgesic for minor to moderate aches and pains, to reduce fever (an antipyretic), and also as an anti-inflammatory drug. Acetaminophen was discovered in 1877 and is the most commonly used drug for pain and fever in the United States and Europe. Marketed in the U.S. since the 1970s, ibuprofen is used for treating pain, fever, and inflammation. Naproxen has been available in the U.S. since 1980 and is used for treating pain, fever, swelling, and stiffness and is the preferred NSAID in patients with a high risk of cardiovascular complications such as stroke and heart attack. The NSAIDs are effective in treating mild to moderate pain and should be considered for the first prior to the use of opioids. As with any medication, there are potential risks, side effects, and complications associated with NSAIDs that include kidney and stomach issues as well as drug interactions (e.g., NSAIDs may reduce the benefit of drugs used for treating hypertension).
Steroidal anti-inflammatory drugs include the corticosteroids cortisone, hydrocortisone, and prednisone and are used to suppress inflammation. The steroids can be injected (e.g., epidural steroid injection) directly into the painful area with nerve blocking agents or they can be taken orally. As with opioids, oral steroids should be used for a short duration (1–2 weeks) to avoid the potential complications associated with long-term usage of steroids (e.g., weight gain, stomach ulcers, osteoporosis, collapse of the hip joint, etc.). Muscle relaxants are sedatives prescribed short term to relieve back pain associated muscle spasms and fibromyalgia. Neuropathic pain is usually treated with tricyclic antidepressants (e.g., amitriptyline, nortriptyline, desipramine, imipramine), anticonvulsants (e.g., gabapentin, valproic acid, pregabalin) and local anesthetics (e.g., lidocaine) or a combination of these drugs.
As this post and the previous post demonstrate, there is a sequential approach to the treatment of pain that involves a drug free approaches and non-opioid therapies. If these modalities fail to alleviate the pain, then opiates can be added to your regimen short term.
Our next post will discuss opiates as a drug class that has alleviated pain but also caused pain.
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Robert G. Bell, Ph.D., is president and owner of Drug and Biotechnology Development LLC, a consultancy to the pharmaceutical industry and academia for biological, drug, and device development.